Here are all the players consistently mentioned in Top 10 conversation, and how many rings they won as a #1 option, best player on the team:
8: Bill
6: Mike
4: Magic, Duncan
3: Bird, Shaq, LeBron
2: Cap, Dream, Kobe, KD
1: Wilt, Logo
0: Oscar, Mailman
Only four players have won more chips as the best player on a championship team. Three of those players (Bill, Mike, Magic) won in the pre-2000 era where few players played beyond 15 years, there was no free agency, etc...
Duncan's 4 chips as a #1 is fair game with LeBron, let's just keep in mind that he won thos four across a 9-year stretch (1999 to 2007) and played 19 total years; got his 5th chip as a (productive) role player. If, hypothetically, LeBron wins a 4th chip this year as a #1, it will be 9 years (2012 to 2020), same amount of time as Duncan hit 4 from first to last, and he still has two years to match Tim at 5...
I'll keep it brief since you asked about Bron's case over Duncan, but it ain't a short case: higher peak dominance, longevity as an elite player, at some point undisputed best active player, better all around game, more iconic postseason moments, more decorated across the board in every category besides rings, better elevator of talent, etc...
I'm a Duncan guy and he can take his resume against anybody at the top, but yall gotta stop this pretending LeBron doesn't even have a case against other great players...
History will be much kinder to Bron than we've been in real time...